Speaker 1: Nuclear power is kind of a hallmark of the modern age. Finally,
Speaker 1: all that nerding out to understand the nature of matter
Speaker 1: and how the atom was put together led to some
Speaker 1: real applications, and wow, did things get real. Nuclear physics
Speaker 1: gave us nuclear weapons and the omnipresent threat of total annihilation,
Speaker 1: but it also gave us nuclear energy an incredible way
Speaker 1: to generate emission free energy from weird little rocks. Later
Speaker 1: this week, we'll dig into the policies and politics of
Speaker 1: all that, whether nuclear power is a net good or
Speaker 1: bad for the environment, and talk to a journalist who
Speaker 1: explored the new pro nuclear environmental movement. But today we're
Speaker 1: going to dig into the science and make sure our
Speaker 1: next conversation is well informed by the science. How does
Speaker 1: it all work? What about salt reactors and pebble fuels?
Speaker 1: What is the future of nuclear technology? Genium? Welcome to
Speaker 1: Daniel and Kelly's Extraordinary Powerful Universe.
Speaker 2: Hello. This is Kelly Waider Smith. I'm a parasitologist who
Speaker 2: also studies space, and we are recording this episode on piden.
Speaker 1: Hi. I'm Daniel. I'm a particle physicist, and I will
Speaker 1: judge anyone who says nuclear instead of nuclear.
Speaker 2: Oh, I mean that's fair. Yeah, or nuclear yeah? Ye,
Speaker 2: Judge away, man, Judge Away.
Speaker 1: I heard a lot of them Texas when I lived there.
Speaker 1: Nuclear power.
Speaker 2: Oh man, how long were you in Texas?
Speaker 1: I went to Rice in Houston. Yeah, and that's where
Speaker 1: you know one of our presidents came from, and he
Speaker 1: said nuclear every single.
Speaker 2: Time Bush went to Rice.
Speaker 1: No, but he's from Texas.
Speaker 2: Oh yeah, got it? Okay, right, But one of.
Speaker 1: The Bushes went to Rice with me? I think with
Speaker 1: George P. Bush, son of Jeb Bush, was a Rice
Speaker 1: with me. Yeah.
Speaker 2: Oh were you two BFFs?
Speaker 3: No?
Speaker 1: Definitely not. Oh all right, I mean just that he
Speaker 1: was very political and I very much wasn't. I don't
Speaker 1: know the guy at all.
Speaker 2: Yeah, got it, got it. What is the most that
Speaker 2: you've ever leaned in too? Celebrating a particularly nerdy holiday?
Speaker 1: I don't know if it counts as celebrating a holiday.
Speaker 1: But during the pandemic, some of our friends and neighbors
Speaker 1: challenged us to a bake off competition who could make
Speaker 1: the most interesting cake with movable parts, which was a
Speaker 1: big engineering challenge. And when we showed up at their house,
Speaker 1: we had to measure the width of their door to
Speaker 1: see if our cake would fit. Because I made this
Speaker 1: enormous landscape with a boat that would go down a
Speaker 1: river and a windmill with pieces that turned. I think
Speaker 1: I took like a week off of work and I
Speaker 1: bought all the marsh mellows and all the rice crispies
Speaker 1: at the grocery store to make this ridiculous landscape.
Speaker 2: Yeah did you win?
Speaker 1: Oh yes, we absolutely destroyed them just by sheer size.
Speaker 1: You know, I was going for like, this thing has
Speaker 1: got a pop. So yeah, it was pretty impressive. I
Speaker 1: gotta say.
Speaker 2: I mean, that's a good way to pass the pandemic.
Speaker 2: Did you take a picture?
Speaker 1: We have a picture somewhere. Absolutely. And then it had
Speaker 1: other weird downstream consequences because nobody could eat that much
Speaker 1: rice crispies, and so we ended up throwing a lot
Speaker 1: of it away, which led to a huge explosion in
Speaker 1: the neighborhood rat population. And then we ended up discovering
Speaker 1: a rat's nest literally, like a mom and ten little
Speaker 1: rat babies near our garbage can. And when you discover
Speaker 1: a rat's nest, the mom will just abandon the babies.
Speaker 1: So then we had like ten cute little rat babies
Speaker 1: and they starved to death because the mom wouldn't come back.
Speaker 1: And you can't feed rat babies. I don't know if
Speaker 1: you know much about rats, but like they have to
Speaker 1: be nursed, and also they can't poop on their own.
Speaker 1: Like rat babies are a whole thing. And so then
Speaker 1: we felt really bad about that, and that's why we
Speaker 1: ended up adopting rats.
Speaker 2: That story was a roller coaster ride, Daniel. There are
Speaker 2: some real highs and real lows there, I know.
Speaker 1: And because we had such a good experience with having
Speaker 1: pet rats, the kids were able to convince me to
Speaker 1: get a dog. So the reason and we now have
Speaker 1: a dog who is an integral part of our family,
Speaker 1: is because I went all out celebrating this crazy engineering challenge. Bakathon.
Speaker 2: Oh my goodness, it is kind of incredible the way
Speaker 2: small things in life can lead you down completely different paths. Well,
Speaker 2: your story is way more wholesome than mine.
Speaker 1: Yeah, what's yours?
Speaker 2: I was born on Molday. So Avagadro's number is what
Speaker 2: six point two three times sent to the twenty third
Speaker 2: or something like that, but October twenty third, and so
Speaker 2: for my junior and senior year of undergrad I had
Speaker 2: chemistry themed birthday parties, and it would be like, uh, yeah, it.
Speaker 1: Sounds really fun. Why didn't I get invited?
Speaker 2: If I had known, you man, you would have been.
Speaker 2: But it was, you know, like how many electrons are
Speaker 2: in beryllium? Wrong drinks?
Speaker 1: And it was.
Speaker 2: Because you know, no one knows that.
Speaker 1: Nobody knows that, because it's chemistry, it's all exceptions.
Speaker 2: That's right, that's right. And you know, my friends didn't
Speaker 2: know chemistry very well either, so it was we had
Speaker 2: a really great time.
Speaker 1: But this is high school, so you're what drinking soda
Speaker 1: or punch or.
Speaker 2: Something undergrad undergrad?
Speaker 1: Undergrad. Oh, so these were fun parties.
Speaker 2: These were fun parties. We were all of legal drinking age,
Speaker 2: and we were careful, we watched out for each other,
Speaker 2: but way less wholesome than a cake with a waterfall.
Speaker 1: Well, it does sound like your parties are maybe the
Speaker 1: only way to make chemistry fun.
Speaker 2: Ah, we did have a good time. The Benzene ring
Speaker 2: and I me and my five friends, six of us total,
Speaker 2: because there's six carbons in a benzene ring.
Speaker 1: And today on the podcast, we're going to be exploring
Speaker 1: how small decisions can lead to big consequences that also
Speaker 1: involve chemistry. Nuclear power is incredible because these tiny, little
Speaker 1: weird rocks can lead to incredible influence on our economy.
Speaker 2: I am always impressed by the way you bring our
Speaker 2: tangents back to the topic.
Speaker 1: Not always easy, but I'm like, wow, we could do
Speaker 1: a whole episode on Kelly's Weird college Parties.
Speaker 2: I think our listenership would go down pretty fast at
Speaker 2: that point. But Okay, so today we're talking about nuclear power,
Speaker 2: and I'm really excited to be talking about these sort
Speaker 2: of advances in nuclear power technology now because when Zach
Speaker 2: and I wrote Soonish, which came out in like twenty seventeen,
Speaker 2: we did some research on advanced nuclear fission reactors. And
Speaker 2: I always have to pause before I say fission and
Speaker 2: fusion because I memorized it in the opposite way initially,
Speaker 2: and so now I will always pause and have to
Speaker 2: think through it.
Speaker 1: But anyway, well, you've got nuclear right. At least you
Speaker 1: didn't say nuclear fusion.
Speaker 2: There you go, that's right now. I'm gonna avoid saying
Speaker 2: that we're too out of a concern for messing it up.
Speaker 2: But we had a chapter on fission and a chapter
Speaker 2: on fusion, but I haven't thought about this in about
Speaker 2: the decades since we researched the topic, and so I'm
Speaker 2: looking forward to your coverage of what the new and
Speaker 2: exciting things are in the world of advanced nuclear reactors.
Speaker 1: Yeah, if we're going to talk about nuclear power, we
Speaker 1: need to understand how it works and how it's changing,
Speaker 1: because it's not a stagnant field, right. Nuclear reactors today
Speaker 1: are not the same nuclear technology your grandparents grew up with,
Speaker 1: and so there's lots of promising directions, some with more waste,
Speaker 1: some with less waste, some with greater risks, some with
Speaker 1: smaller risks, and so it's crucial to understand the whole
Speaker 1: spectrum of possibilities in order to have an informed conversation
Speaker 1: about nuclear politics, which we're going to have in the
Speaker 1: next episode. So I was curious what listeners thought about
Speaker 1: the future of nuclear technology. What have they heard about
Speaker 1: in terms of advanced nuclear reactors. So I went out
Speaker 1: there and I asked our group of volunteers what is
Speaker 1: the most promising advancement in nuclear power technology. Here's what
Speaker 1: they had to say. If you'd like to play for
Speaker 1: a future episode of the podcast, we really really really
Speaker 1: really wanted to hear your voice on the pod right
Speaker 1: to us to questions at Danielankelly dot org. So think
Speaker 1: about it for a minute before you hear these answers.
Speaker 1: What do you think is the most promising advancement in
Speaker 1: nuclear technology? Here's what our listeners have to say.
Speaker 3: Just for Kelly, I've heard of biologists working on microbes
Speaker 3: to solve our nuclear waste problem.
Speaker 1: Somehow they eat the nuclear waste.
Speaker 2: No idea how it works, but heyo biology.
Speaker 1: There are a few promising advances, but the most promising
Speaker 1: comes in the form of superpowers from what used to
Speaker 1: be just ordinary bug bites.
Speaker 2: But where I would like to see more study is
Speaker 2: in medical applications such as radiation treatment for cancer.
Speaker 4: Not running redundant systems through the same conduent.
Speaker 1: I think the most promising advance is the potential to
Speaker 1: use what used to be waste as fuel for a
Speaker 1: whole new set of nuclear reactions, using or repurposing fuel
Speaker 1: that has been expent. Reusing the nuclear waste as opposed
Speaker 1: to story without a doubt, fusion decreasing the waste.
Speaker 2: People have probably paid a lot of money in PI
Speaker 2: to make me think of thorium, So I'm going to say.
Speaker 4: Thorium SMRs, which are those small modular reactors micro nuclear
Speaker 4: energy where they're able to go much smaller nuclear power stations.
Speaker 3: I guess to me what seems most interesting is the
Speaker 3: liquid thorium salt reactors, which kind of can use up
Speaker 3: the material really well from what I understand, or have
Speaker 3: beneficial byproducts, and are also seemed a lot safer.
Speaker 5: The very teeny tiny amount of nuclear material that's necessary
Speaker 5: now to create vast amounts of energy, which means it's
Speaker 5: not as big of a risk of a meltdown and
Speaker 5: things like that.
Speaker 4: Perhaps the reactors are more efficient, more manageable, less likely
Speaker 4: to melt down in the case of an earthquake or
Speaker 4: tsunami or other natural disaster.
Speaker 2: As usual, a lot of fantastic answers. We're not going
Speaker 2: to be talking too much about fusion today, but if
Speaker 2: you want to hear more about fusion, a little while back,
Speaker 2: we recorded an episode on whether or not there would
Speaker 2: be enough fuel available to run fusion plants, and we
Speaker 2: go through the science of fusion reactors there as well and.
Speaker 1: Throw cold water on that whole industry.
Speaker 2: Well, I remember we were optimistic at the end that
Speaker 2: you know, once we got fusion going, maybe we'd get
Speaker 2: the technologies needed to make like deuterium and trinium more available,
Speaker 2: but maybe maybe maybe, But all right, but now today
Speaker 2: we're talking about fission reactors in particular.
Speaker 1: Yes, exactly, and so let's dig in first and make
Speaker 1: sure we killing everybody understands the difference between fission and aufusion,
Speaker 1: because they're closely related but very very different. Right. So,
Speaker 1: fusion is what powers the universe, it's what makes stars bright,
Speaker 1: it's where all the energy on Earth comes from. It's
Speaker 1: really almost ubiquitous in the universe. Fission is much more
Speaker 1: more rare. A fusion is basically when you take light
Speaker 1: elements hydrogen, helium, things lighter than iron, and turn them
Speaker 1: into heavier elements, so you stick them together and energy
Speaker 1: is released. So, for example, if you take hydrogen and
Speaker 1: you stick it together to make helium, energy is released
Speaker 1: and the mass of that helium is less than the
Speaker 1: mass of the hydrogen's combined, so energy is released there
Speaker 1: in fusion. So that's fusion is you take light elements,
Speaker 1: you stick them together, and energy is.
Speaker 2: Released, which sounds easy but requires super extreme conditions to
Speaker 2: make happen, which is why it's been so hard to
Speaker 2: make a fusion plant exactly.
Speaker 1: Those nuclear i do not want to stick together. They
Speaker 1: have coolombic repulsion. You need high density, high pressure, all
Speaker 1: sorts of stuff to make that happen. If you make
Speaker 1: it happen, it releases energy and that helps it happen.
Speaker 1: So it's this cool ignition process where the energy released
Speaker 1: from fusion helps make the next round of fusion happen.
Speaker 1: And you have a sort of similar chain reaction going
Speaker 1: on in fission. But fission is the other direction. Fission says,
Speaker 1: take a heavy element, break it open to make it
Speaker 1: a lighter element, and energy is released. In that case,
Speaker 1: you might wonder a whole lot a second, didn't Daniel
Speaker 1: just tell us that when you squeeze light elements together
Speaker 1: to make them heavy, energy is released. Now he's saying,
Speaker 1: if you break elements apart to make them lighter, energy
Speaker 1: is released. And yeah, those do sound contradictory. And the
Speaker 1: difference is whether you're starting with light or heavy elements. So,
Speaker 1: if your elements are light like below iron, specifically, fusing
Speaker 1: them together releases energy, making them heavier towards iron. If
Speaker 1: your elements are heavy, like uranium, something heavier than iron,
Speaker 1: breaking them apart, bringing them again towards iron releases energy.
Speaker 1: So basically, anytime you're taking a step towards iron, which
Speaker 1: is like the middle of the periodic table, you are
Speaker 1: releasing energy.
Speaker 2: Can you remind me? Inside of stars is that where
Speaker 2: we get iron and everything up from that? What is
Speaker 2: the breakof there?
Speaker 1: Yeah, it's about iron. So inside stars you mostly have hydrogen.
Speaker 1: Hydrogen fuses to me helium, and then that fuses to
Speaker 1: make neon and carbon and oxygen and heavier stuff silicon, nickel,
Speaker 1: all the way up to iron. And that whole process
Speaker 1: keeps the star hot because every step along the way
Speaker 1: releases energy. What happens when you start fusing iron. If
Speaker 1: a star is really big and really hot and has
Speaker 1: the high enough temperature tofuse iron, that cools the star.
Speaker 1: It takes some energy because it costs energy to fuse
Speaker 1: iron together into heavier stuff that cools the star and
Speaker 1: kills it. So that's the end of a star's life
Speaker 1: when it has enough iron in it that that iron
Speaker 1: starts to fuse and cools the star. So you can't
Speaker 1: really make stuff heavier than iron in any substantial quantities
Speaker 1: inside a star. To make the stuff heavier than iron,
Speaker 1: uranium platinum, gold, all that good sparkly stuff. You need
Speaker 1: other kinds of events collisions of neutron stars and supernova
Speaker 1: for example, very briefly have the conditions to make those.
Speaker 1: It costs a lot of energy to make those very
Speaker 1: heavy stuff.
Speaker 2: Okay, interesting, all right, So fusion really hard to do
Speaker 2: unless you're in the sun. Fission much easier to do
Speaker 2: using big stuff.
Speaker 1: Yeah, exactly. So find some uranium, shoot it with a neutron,
Speaker 1: for example. The uranium will break apart and it will
Speaker 1: release more neutrons, and those neutrons can hit more uranium atoms,
Speaker 1: which can release more neutrons. So if you have it
Speaker 1: set up correctly, like your fuel is dense enough so
Speaker 1: there's a high enough chance for that neutron to hit
Speaker 1: another uranium nucleus, and the neutrons are at the right
Speaker 1: speed to make that happen, Like really fast neutrons are slow,
Speaker 1: neutrons might be more or less likely to make the
Speaker 1: uranium nucleus break up. We'll dig into that in a minute.
Speaker 1: Then you can get a chain reaction. If it's a
Speaker 1: runaway reaction, like the fuel is very very dense and
Speaker 1: things are growing exponentially, you get a bomb that's a
Speaker 1: nuclear bomb.
Speaker 2: Don't do that, folks, not in your basement.
Speaker 1: If you manage it so that the rates at which
Speaker 1: one nucleus is spurring the fission of another nucleus, you
Speaker 1: regulate it to be steady, then that's a reactor. It's
Speaker 1: releasing energy, but it's not growing exponentially out of control.
Speaker 2: And why is uranium the sweet spot on the periodic
Speaker 2: table for stuff you want for your fission reactor.
Speaker 1: It's not really that sweet. It's just something that's around
Speaker 1: and for a while, is pretty cheap to mine. As
Speaker 1: we'll hear about, there are lots of things that are fissile.
Speaker 1: It's just a question of what's present in the Earth's crust,
Speaker 1: what's cheap to mine, what's not already being used by
Speaker 1: other industries. And so uranium is actually not a great
Speaker 1: source for fuel because most of the uranium we find
Speaker 1: in the Earth's crust is an isotope that's not great
Speaker 1: for fission. It's uranium two thirty eight. Uranium two thirty
Speaker 1: five is pretty good for fission, but most of what
Speaker 1: we find in the ground is uranium two thirty eight.
Speaker 1: Less than one percent of natural uranium is the kind
Speaker 1: we want so as we'll talk about there are other
Speaker 1: options like thorium that are maybe even better for nuclear fuel.
Speaker 2: Let's dig in then to uranium a bit more. So
Speaker 2: you said, we mostly find uranium two thirty eight, but
Speaker 2: we need two thirty five. How do you get it
Speaker 2: from two thirty eight to two thirty five?
Speaker 1: So what you do is just enrich it. Like remember
Speaker 1: chemistry lab when you have like a pilot goo and
Speaker 1: you need to separate it out into the elements of
Speaker 1: the goo. You can like boil it and one will
Speaker 1: boil off, or you can, you know, try to make
Speaker 1: them settle or something. There's lots of different tricks in chemistry,
Speaker 1: and what they typically do, because one of them is
Speaker 1: heavier than the others, they use a centrifuge. So if
Speaker 1: you remember, like hearing about Iranian centrifuges as they're trying
Speaker 1: to purify uranium, that's a typical strategy because they have
Speaker 1: different masses, is use a centrifuge, and so you can
Speaker 1: enrich your uranium. Run these centrifuges more and more and
Speaker 1: filter out the two thirty eight you get a higher
Speaker 1: and higher fraction of two thirty five.
Speaker 2: I've always been unreasonably concerned about USB sticks after hearing
Speaker 2: the story about how the virus that messed up the
Speaker 2: Iranian centrifuges was brought in by somebody who just had
Speaker 2: a USB stick that had the virus and then when
Speaker 2: they stuck it into one of the computers, it spread,
Speaker 2: which is like amazing, And I'm sure there's a lot
Speaker 2: of other things I should be way more worried about,
Speaker 2: and of course, like nobody really cares about what I've
Speaker 2: got going on in my office. I remember thinking that
Speaker 2: was just like such a cool story, and now every
Speaker 2: time I see a USB stick, I think, h's on you.
Speaker 1: It's a pretty cool story about engineering, like cyber espionage,
Speaker 1: pretty cool stuff. But are you running a uranium centrifuge
Speaker 1: and your science form?
Speaker 2: Well, I mean, why would I admit something like that
Speaker 2: to you, Daniel on air? That's ridiculous, But you wouldn't
Speaker 2: be a good spy at all. But yeah, I mean
Speaker 2: the story there is that like this virus messed up
Speaker 2: their centrifuges because there was concerned that Iran was turning
Speaker 2: two thirty eight into two thirty five so that they
Speaker 2: could start making weapons, and by messing up that process,
Speaker 2: by messing up all of their super expensive centrifuges, we
Speaker 2: at least managed to slow them down.
Speaker 1: And so you need to enrich uranium because you need
Speaker 1: dense enough source of the good stuff uranium two thirty five.
Speaker 1: If you don't have a dense enough then it makes
Speaker 1: neutrons when it splits, but then those neutrons don't find
Speaker 1: other two thirty five nuclei and it just peters out.
Speaker 1: So you need to be dense enough. You need to
Speaker 1: enrich it up to like two or five percent. Doesn't
Speaker 1: have to be pure uranium two thirty five at all,
Speaker 1: like two to five percent, But this is still kind
Speaker 1: of a problem because you end up mostly just burning
Speaker 1: the U two thirty five, and the U two thirty
Speaker 1: eight is just sitting there, and it sits there and
Speaker 1: makes heavy elements which are bad. So this is like
Speaker 1: really not a great mixture. A lot of the waste
Speaker 1: comes from U two thirty being in the reaction, not
Speaker 1: being part of it, and then getting converted to toxic stuff,
Speaker 1: so it's not like a great situation. But what you
Speaker 1: need to do to make uranium fission happen is to
Speaker 1: enrich your fuel. So you have like two to five percent.
Speaker 1: Then you also have to engineer the speed of those
Speaker 1: neutrons to make things work.
Speaker 2: So if you want the neutrons to be going quickly
Speaker 2: so that they're bumping into the two thirty five, why
Speaker 2: would you want to slow them down. It seems like
Speaker 2: more neutrons is you know, that's better, that's more energy.
Speaker 1: Yeah, it seems like fast neutrons are good, right, The
Speaker 1: whole point is to get energy out. Well, the thing
Speaker 1: is that you two thirty five is a little personicity,
Speaker 1: Like if you shoot fast neutrons added sometimes they will
Speaker 1: just go right through. They will not make it fizz.
Speaker 1: What is the very many fission? They will not make
Speaker 1: it fission. Can want atom fission? That seems weird.
Speaker 2: They will not fission it. I don't know.
Speaker 1: I will not stand for that anyway. YouTube thirty five
Speaker 1: likes slower neutrons. YouTube thirty eight likes faster neutrons. But
Speaker 1: uranium fission doesn't make enough fast neutrons to sustain fusion
Speaker 1: with two thirty eight, So you got to use the
Speaker 1: two thirty five, and you've got to slow down the
Speaker 1: neutrons untill they're in the sweet spot for making other
Speaker 1: uranium nuclei go. So you've got to moderate the temperature.
Speaker 1: So you hear a lot about neutron moderation, and so
Speaker 1: the way they do this is they use water. So
Speaker 1: you have like these fuel rods and then you have
Speaker 1: water around them, which is also good for cooling them
Speaker 1: and extracting the energy, but it slows down the neutrons
Speaker 1: to keep the reaction going. It's a little counterintuitive, but
Speaker 1: this stuff is a little bit sensitive.
Speaker 2: I thought the answer because my memory is great. I
Speaker 2: know I wrote about this about a decade ago, but
Speaker 2: I thought the answer was going to be you don't
Speaker 2: want the neutrons to go too fast because you don't
Speaker 2: want the reaction to go too fast and overheat. But
Speaker 2: that's not the answer. Was misremembering. Okay, so you've got
Speaker 2: the water. The water is heating up. How does this
Speaker 2: create energy? Does the water turn into steam and turn
Speaker 2: a turbine or is the energy being collected in some
Speaker 2: other way?
Speaker 1: Yeah, so not directly. The most popular technology is called
Speaker 1: a pressurized water reactor. You have uranium rods surrounded by water.
Speaker 1: The water moderates the speed of the neutrons, also keeps
Speaker 1: the core from overheating, and then you've got to extract
Speaker 1: the energy from that water, so it heats up the water.
Speaker 1: How do you get the energy out of the water,
Speaker 1: typically a turbine. Right. Also, that water becomes radioactive, so
Speaker 1: you want to buffer yourself from that. So typically there's
Speaker 1: like a heat exchange or with that water well then
Speaker 1: heat up other water. You have like these two corkscrews
Speaker 1: that interwove with each other. It's sort of like electrical inductance,
Speaker 1: but with heat or just basically a radiator. You have
Speaker 1: this water pass near other water and the hot, nasty,
Speaker 1: radioactive water heats up the clean cold water, which then
Speaker 1: boils into steam and then turns a turbine. So that's
Speaker 1: the most common steps, and this is called a light
Speaker 1: water thermal reactor, sometimes known as a pressurized water.
Speaker 2: Reactor if I'm remembering correctly. The reason that light water
Speaker 2: thermal reactors are the most common kind of reactor out
Speaker 2: there isn't because we were super careful and we looked
Speaker 2: at all the possible reactor designs and there was definitely
Speaker 2: none that could be better than this, but because we
Speaker 2: sort of happened upon one design because it fit really
Speaker 2: well in our submarines that we wanted to have nuclear
Speaker 2: powered Is that story correct.
Speaker 1: Yeah, that story is correct. In the fifties that were
Speaker 1: exploring lots of different technologies, some of which we're going
Speaker 1: to talk about thorium and other technologies. But this was
Speaker 1: a good fit for the military because one of the
Speaker 1: waste products of this reactor is plutonium, which the military
Speaker 1: wanted to produce anyway for their weapons. Also, if you're
Speaker 1: on a ship or a submarine places that the military
Speaker 1: wanted to put nuclear power, water is plentiful. It's not
Speaker 1: so hard to find water. And so these light water
Speaker 1: thermal reactors were explored for the military, and the government
Speaker 1: basically stopped funding all these other directions. The government's decisions
Speaker 1: early on determined like what was explored and what was
Speaker 1: made economically feasible. No private industry was like involved in
Speaker 1: developing nuclear technology. This is definitely like a public investment
Speaker 1: by the government.
Speaker 2: All Right, well, let's take a break, and when we
Speaker 2: get back, we'll talk about some of the risks of
Speaker 2: this particular kind of reactor. All Right, we just finished
Speaker 2: talking about how light water thermal reactors work. Let's talk
Speaker 2: about some of the risks of this particular kind of reactor.
Speaker 2: Go for it, Daniel, You're turning to be the negative Nelly.
Speaker 1: I don't know how to order them, but you know
Speaker 1: it's called a pressurized water reactor. So let's start with
Speaker 1: the pressurized water. You got this water that you want
Speaker 1: to keep liquid because you want to keep flowing. It's
Speaker 1: easiest to control if it's liquid, it's a more efficient
Speaker 1: heat transfer. If it's liquid, you got other things like
Speaker 1: control rods, graphite you want to dip in the liquid.
Speaker 1: So basically, you want to keep this stuff liquid. But
Speaker 1: it's also really hot. So how do you keep something
Speaker 1: liquid if it's really hot. Chemistry tells us you need
Speaker 1: to keep it at high pressure, right, Basically, build really
Speaker 1: strong vessel and force the water to have high pressure
Speaker 1: so it doesn't turn into steam. We're talking like one
Speaker 1: hundred to one hundred and fifty atmospheres of pressure, so
Speaker 1: really high pressure stuff. This is kind of dangerous because
Speaker 1: very high pressure. Right, if you lose containment, you know,
Speaker 1: you can imagine like a rivit pops and steam shoots out. Right,
Speaker 1: it's super hot, it's super high pressure. It's going to
Speaker 1: burn somebody. Also, as soon as you lose pressure, you're
Speaker 1: losing your coolant. Right, This water is crucial to keep
Speaker 1: in the core from overheating, right, we don't want the
Speaker 1: core to turn into a bomb. We don't want the
Speaker 1: energy from that thing to like melt the reactor itself.
Speaker 1: So you've got to keep the temperature at a certain
Speaker 1: level so it doesn't melt down. That's literally what melting
Speaker 1: down happens. But as soon as you lose containment of
Speaker 1: your water, then you're losing your coolant and boom you
Speaker 1: have an overheating and a meltdown. This is what happened
Speaker 1: a three mile island. Like one of the water hatches
Speaker 1: jammed at Fukushima. One of the water pumps was knocked out,
Speaker 1: and in Chernobyl the water boiled off. And so this
Speaker 1: is really important to keeping this whole thing going is
Speaker 1: keeping this very high water pressure and that's not easy
Speaker 1: to do. And if it fails in any way, boom
Speaker 1: you have a disaster.
Speaker 2: So one, you have to worry about the boom, but
Speaker 2: do you also have to worry about when the water
Speaker 2: gets out it's a steam. Can that steam travel great
Speaker 2: distances or does that tend to settle near the plant?
Speaker 1: If you have any loss of containment, then the clouds
Speaker 1: can travel great distances, like what happened at Chernobyl is
Speaker 1: these clouds of radioactive dust and steam and all sorts
Speaker 1: of stuff drifted over Europe and like caused cancers all
Speaker 1: over Europe. It was really bad. Yes, it's terrible.
Speaker 2: This pressurized containment problem. Is that only a problem for
Speaker 2: light water thermal reactors or is this a problem for
Speaker 2: some of the other reactor types we're gonna talk about
Speaker 2: as well.
Speaker 1: It's only a problem for light water thermal reactors. For
Speaker 1: these pressurized water reactors, and there's lots of designs inspired
Speaker 1: specifically by avoiding having high pressure liquid, and we'll talk
Speaker 1: about some of those, but this is by far the
Speaker 1: most common, Like something like eighty five percent of all
Speaker 1: reactors in the world are pressurized water reactors.
Speaker 2: All right, so the pressure part is not great. Let's
Speaker 2: move on to another risk.
Speaker 1: Yeah, So the U two thirty eight that's mostly what's
Speaker 1: in your fuel rods, is not burning, it's not undergoing fission,
Speaker 1: but it does get hit with a lot of neutrons
Speaker 1: and it breaks down into other stuff. It can make
Speaker 1: things like plutonium, right, plutonium two thirty nine, for example,
Speaker 1: or plutonium two thirty eight. Two thirty eight is short
Speaker 1: lived and very very toxic. It has a half life
Speaker 1: of eighty eight years, but two thirty nine has a
Speaker 1: half life of twenty four thousand years. So you got
Speaker 1: sort of two different angles here. One is you're making
Speaker 1: weapons fuel, right, Plutonium is excellent for making weapons, and
Speaker 1: you're creating stuff that has like thousands of years or
Speaker 1: sometimes millions of years, like neptunium two thirty seven has
Speaker 1: a two point one million year half life. This stuff
Speaker 1: is toxic for a long long time.
Speaker 2: So how big is the weapons risk? If you run
Speaker 2: one of these plants for a decade, does that give
Speaker 2: you enough plutonium to make a big bomb or do
Speaker 2: you need to run it for two hundred years or
Speaker 2: does it depend on a lot of other factors. How
Speaker 2: much weapons grade radioactive material is produced?
Speaker 1: Not a lot, but you don't need a lot to
Speaker 1: make a few bombs, right, And in order to have
Speaker 1: like geopolitical deterrence, you don't need a huge number of bombs.
Speaker 1: Like North Korea started out with like three, four or
Speaker 1: five bombs, but that completely changed the politics are dealing
Speaker 1: with North Korea. Right, one bomb dropped on Soul is
Speaker 1: a huge impact. And so yeah, you can make a
Speaker 1: weapons significant amount of plutonium without a huge industry. Absolutely.
Speaker 2: This is one of the things that's so frustrating to
Speaker 2: me about nuclear power is it's so clearly a technology
Speaker 2: that would be you know, great in this world where
Speaker 2: we're dealing with climate change, if only humans weren't so humany.
Speaker 1: Yeah, exactly. And you know, there's two sides to this,
Speaker 1: as we'll dig in when we talked to Becca later
Speaker 1: this week. Like most of the stuff, when you make it,
Speaker 1: you just keep it on site at the reactor, you know,
Speaker 1: drive it all around. But there's this question of like
Speaker 1: where's it going to go long term? You know, like
Speaker 1: can we just bury it in the ground, Can we
Speaker 1: put it in Yaka Mountain? Should we launch it into space?
Speaker 1: Isn't that a terrible idea? And you know a lot
Speaker 1: of people are concerned about that, and the environmental is
Speaker 1: very concerned about that. On the other hand, you have
Speaker 1: to remember that this stuff has a finite lifetime, right,
Speaker 1: This stuff will decay away into something non toxic after
Speaker 1: hundreds or thousands of years. But if you're making really
Speaker 1: terrible forever chemicals with fossil fuels, that stuff is poisoned forever.
Speaker 1: Like literally you come back to Earth in five billion years,
Speaker 1: it'll still kill you. And so we should remember that
Speaker 1: a long lifetime is still shorter than an infinite lifetime.
Speaker 2: Speaking of sending nuclear materials to space, once there was
Speaker 2: a piece of I think it was polonium that was
Speaker 2: being sent up, and the rocket blew up and the
Speaker 2: radio active materials sort of scattered over the Soviet Union.
Speaker 2: And then the Soviet Union also sent up a bunch
Speaker 2: of tiny nuclear reactors to power some of their satellites,
Speaker 2: and one of those satellites went rogue, and the nuclear
Speaker 2: material that powered that reactor scattered over northern Canada. So,
Speaker 2: you know, sending the stuff into space could go wrong
Speaker 2: and scatter it over a big stretch of land if
Speaker 2: anything happens to that rocket. These are complicated problems.
Speaker 1: Basically, each time you do a launch, it's a potential
Speaker 1: dirty bomb, right.
Speaker 2: Yeah, yeah, you gotta be really careful about this stuff.
Speaker 1: Nobody wants dirty bombs. I don't want clean bombs or
Speaker 1: dirty bombs, but I definitely don't want dirty bombs.
Speaker 2: Yeah, no, thumbs down to dirty bombs. We both agree.
Speaker 1: And there's another factor to this waste, which is the
Speaker 1: waste produced in the actual reactions is not that large.
Speaker 1: The total amount, the volume of waste produced worldwide in
Speaker 1: the history of the industry is not huge. It's like
Speaker 1: a football field size, But that's not all of the waste. Like,
Speaker 1: in order to get uranium out of the ground, you
Speaker 1: have to mine it, and there's a lot of waste
Speaker 1: produced in that mining. Some of that is also radioactive
Speaker 1: and toxic and much much higher volumes. So when you
Speaker 1: hear people talk about the waste from nuclear power plants,
Speaker 1: guess the actual waste from the reactions is quite small
Speaker 1: and very toxic, But there's a much larger volume of
Speaker 1: waste produced in the processing to get the fuel to
Speaker 1: the plant. That's not always considered in those conversations.
Speaker 2: And what do we do with that waste?
Speaker 1: Yeah, that waste we store on site near the mines,
Speaker 1: and like that's dangerous also when you're polluting water tables
Speaker 1: and so yeah, oh.
Speaker 2: Yeah, yeah, no easy answers. Okay, all right, so let's
Speaker 2: move on. We've now talked about the benefits and risks
Speaker 2: of the light water thermal reactor. Let's move on to
Speaker 2: some of the alternative designs that have sort of different
Speaker 2: problems and different benefits. Let's start with the boiling water reactor.
Speaker 1: So the most obvious things they do is to focus
Speaker 1: on the pressure of the water. Can you make a
Speaker 1: design for a nuclear reactor core that doesn't require high
Speaker 1: pressure water. So there's a boiling water reactor that says, hey,
Speaker 1: let's just let the water boil and turn into steam.
Speaker 1: That makes the heat transfer less efficient, so you have
Speaker 1: to build it larger so you can have like more
Speaker 1: of this steam and the water of course is less
Speaker 1: dense because now it's steam, but it lets you lower
Speaker 1: the pressure down to like seventy five atmosphere because now
Speaker 1: you can just have the water turn into steam and
Speaker 1: then you use that steam directly to generate energy, basically
Speaker 1: what you were saying earlier. So instead of having this
Speaker 1: like weird heat exchanger system where the hot water boils
Speaker 1: other clean water, you just use the dirty water directly
Speaker 1: to make your steam.
Speaker 2: So that seems clearly better than the other method. Is
Speaker 2: there a downside to this reactor?
Speaker 1: Downside is now you are using irradiated water and steam
Speaker 1: to generate your energy, and so it's a little less
Speaker 1: contained like now involved in these turbines and stuff like that,
Speaker 1: So you haven't decoupled the energy production and the electricity production,
Speaker 1: so there's some risks there. Also, it has to be larger,
Speaker 1: and so for example we're talking about later the benefits
Speaker 1: of small modular reactors. Those require technology that has very
Speaker 1: dense fuel and very small reactor core, and you can't
Speaker 1: do that with a boiling water reactor. You need a
Speaker 1: large core because this steam isn't as dense and the
Speaker 1: heat transfer is less efficient.
Speaker 2: I think I'm still a little confused about the decoupling thing.
Speaker 2: Is the point that you're going to at some point
Speaker 2: also need to replace the turbine and now you have
Speaker 2: a radioactive turbine and that's the problem.
Speaker 1: Yeah, exactly.
Speaker 2: Okay, so about what percent of our reactors right now
Speaker 2: are boiling water reactors.
Speaker 1: These are like fifteen percent, so a good number of
Speaker 1: these and this has proven technology, right. I mentioned this
Speaker 1: because some of the stuff we're talking about later is
Speaker 1: like a little bit more speculative. But these are reactors
Speaker 1: that are running, we know how they work. We have
Speaker 1: people out there in the world with experience running these reactors.
Speaker 1: It's not speculative, it's not experimental technology. This is like
Speaker 1: it's been proven. And then the last piece are heavy
Speaker 1: water reactors like five percent of the reactors out there,
Speaker 1: say well, let's just take the pressurize water and replace
Speaker 1: it with heavy water. So heavy water is not just
Speaker 1: like water that feels heavier. It's water where some of
Speaker 1: the hydrogen has been replaced by an isotope of hydrogen.
Speaker 1: So instead of just having like a proton as for
Speaker 1: the hygen, you have like a proton and a neutron together. Basically, deuterium,
Speaker 1: one of the important fuels for fusion, can be used
Speaker 1: as an alternative moderator in your reaction and a heavy
Speaker 1: water reactor.
Speaker 2: And you had told me in that fusion episode that
Speaker 2: there's not a lot of deuterium. Is that right? Is
Speaker 2: getting enough deuterium one of the difficult things of running these.
Speaker 1: Reactors, Yeah, exactly. Deutarium is not free and it's not
Speaker 1: that easy to filter out. I mean, there's a lot
Speaker 1: of it out there, but it's a little bit rare.
Speaker 1: And so heavy water is an excellent moderator because it
Speaker 1: will slow the neutrons down to the speed that U
Speaker 1: two thirty five needs it, but it never captures them right,
Speaker 1: and so if lets them fly through. Basically it's perfect
Speaker 1: at converting fast neutrons to slow neutrons without ever gobbling
Speaker 1: up the neutrons, and so you can actually run a
Speaker 1: heavy water reactor without using enrichment. You can have a
Speaker 1: much lower density of you two thirty five in your
Speaker 1: fuel for a heavy water reactor. So there's pros and
Speaker 1: cons there.
Speaker 2: Okay, so it's good to use more two thirty five.
Speaker 1: Lets you use less two thirty five. Usually you need
Speaker 1: more two thirty five so the neutrons can find other
Speaker 1: two thirty five nuclei. But here heavy water converts all
Speaker 1: the fast neutrons into exactly the right neutrons that U
Speaker 1: two thirty five needs, so that even if you don't
Speaker 1: have an enriched fuel, those neutrons will find enough two
Speaker 1: thirty five nuclei to get the reaction to keep going.
Speaker 2: But two thirty eight is the stuff that turns into
Speaker 2: the nasty byproducts, right, yeah, exactly. So now you've got
Speaker 2: the same kinds of waste and you have the same
Speaker 2: confinement issues as the light water reactor.
Speaker 1: Yeah, you still have to keep high pressure here because
Speaker 1: you have the same issues. You want to keep the
Speaker 1: water liquid, et cetera. So the heavy water reactor is
Speaker 1: one variation on the pressurized water reactor. It's not a
Speaker 1: boiling water reactor.
Speaker 2: Okay, so you still have the same problems with waste
Speaker 2: and the same problems with pressure, but you don't have
Speaker 2: to start the process by enriching the uranium as much exactly. Okay,
Speaker 2: all right, so we've gone through the main kinds of
Speaker 2: currently existing nuclear fission reactors that are out there. Let's
Speaker 2: take a break, and when we get back, let's talk
Speaker 2: about some of the more advanced designs that are being
Speaker 2: researched at the moment. And we're back, all right. So
Speaker 2: we talked about the most common nuclear reactor designs that
Speaker 2: we've got at the moment, and now we're going to
Speaker 2: talk about some more advanced designs that are being researched.
Speaker 2: So Daniel tell us about gas cooled reactors.
Speaker 1: Yeah, so these are super cool ha haha. The idea
Speaker 1: is to use something like helium to cool your reactor.
Speaker 1: Helium is excellent because it's a noble gas. It hardly
Speaker 1: ever reacts, It likes to ignore everything, so it's basically inert.
Speaker 1: It's a very high heat capacity, so it will absorb
Speaker 1: a lot of heat. So take your water out and
Speaker 1: replace it with helium. But the water also is doing
Speaker 1: two jobs. Right. The water was not just keeping your
Speaker 1: reactor from overheating, it was also moderating the neutron speed.
Speaker 1: So they were just right forgetting the U two thirty
Speaker 1: five to do its thing. So now you need something
Speaker 1: else to do that moderation, and so they use graphite,
Speaker 1: either rods of graphite that you insert between the rods
Speaker 1: of fuel, or you can take the uranium and code
Speaker 1: it in graphite. Graphite is awesome because it will moderate
Speaker 1: the temperature and it's like almost indestructible. You cannot get
Speaker 1: a nuclear reactor up to high enough temperatures to melt
Speaker 1: this graphite. So, for example, you cot your uranium in graphite.
Speaker 1: It does the moderation and it's basically impossible to have
Speaker 1: a leak or a meltdown or to lose containment because
Speaker 1: the graphite is really going to wrap it up forever for.
Speaker 2: This hot stuff that's happening. Do you have a container
Speaker 2: of water that makes the steam that turns the turbine?
Speaker 2: Is that where the power part happens.
Speaker 1: Yeah, So the uranium is wrapped in graphite, that whole
Speaker 1: thing is surrounded by helium. Then the helium has a
Speaker 1: heat exchanger to water and then that water turns turbines.
Speaker 1: We should do a whole episode about like why we
Speaker 1: still use steam driven turbines, Like we have this incredible
Speaker 1: modern age technology, and in the end it's basically a
Speaker 1: steam engine. Yeah, I think that's super fascinating. But yeah,
Speaker 1: so uranium surrounded in graphite covered in helium, and then
Speaker 1: the helium heats water, which turns the turbine, which generates
Speaker 1: electricity which powers your phone.
Speaker 2: Okay, so I've got graphite in my pencil, and when
Speaker 2: I go and I draw something and I shade it in,
Speaker 2: I always have to like brush away the graphite because
Speaker 2: it's all like dusty and stuff. Do you have a
Speaker 2: similar problem with like the uranium pebbles rubbing up against
Speaker 2: each other and graphite becomes a powder. Do you have
Speaker 2: to worry about that powder?
Speaker 1: Graphite is really complex stuff and there's lots of different
Speaker 1: forms of it, and so the kind that's in your
Speaker 1: pencil is like a very very soft kind of graphite.
Speaker 1: You can also make a very very durable, very hard graphite,
Speaker 1: and that's the kind they use. So nobody is like
Speaker 1: going to be drawing portraits of people with graphite pebble fuel.
Speaker 1: But you're right, there is some graphite dust produced, and
Speaker 1: we do have to worry about that. But this is
Speaker 1: very cool technology. They call it pebble fuel. Basically, there's
Speaker 1: no meltdown risk here at all. It's really amazing.
Speaker 2: So why don't we have these yet?
Speaker 1: Then, so we do have some of these. There are
Speaker 1: seven of them that have been ever made. It's sort
Speaker 1: of experimental. It's a little tricky because in order for
Speaker 1: it to work, you have to have very highly enriched fuels.
Speaker 1: They call these h al EU highly enriched fuels, and
Speaker 1: that's like five to twenty percent enrichment, and so this
Speaker 1: is much more enriched than the typical stuff. But it
Speaker 1: allows for very small, very dense reactor core, and it
Speaker 1: allows for small, modular reactors. The idea is like, don't
Speaker 1: build this like huge plant that takes an enormous amount
Speaker 1: of space and produces energy for like half of California.
Speaker 1: Shrink the reactors, make them like the size of a
Speaker 1: shipping container, and then you can produce them at scale,
Speaker 1: so now they become modular. Every reactor we've ever built
Speaker 1: is basically a one off bispoke design, which is one
Speaker 1: reason why they take like twenty years to build and
Speaker 1: to regulate and to check and to verify that it's
Speaker 1: actually going to work. Right, if you had a plant
Speaker 1: to pump these things out, and you knew every single
Speaker 1: one was the same, you could develop once the technology
Speaker 1: and then pump them out. And the idea is that
Speaker 1: you could distribute them to lots of places where otherwise
Speaker 1: there isn't the market for nuclear energy remote places, rural places,
Speaker 1: so you'd have fewer bigger plants and more small plants.
Speaker 1: That's enabled four technologies to have a very small core.
Speaker 2: Okay, awesome, you've got these cheaper modular reactors. You still
Speaker 2: have to worry about bad byproducts being made with those
Speaker 2: uranium pebbles eventually, right you do.
Speaker 1: The pebble fuel itself is fascinating because you can use
Speaker 1: it over and over again. It doesn't use up all
Speaker 1: the fuel immediately, so the pebble remains in the core
Speaker 1: for like three years, and then they circulate it in
Speaker 1: and out several times to burn it up, so like
Speaker 1: a single pebble, you can use it for decades and
Speaker 1: then in the end, all the fuel is still encased
Speaker 1: in your graphite, right, so all the bad stuff is
Speaker 1: also inside the graphite, so basically it comes out already sealed.
Speaker 2: That's amazing. Do you not have to worry about the
Speaker 2: helium because it doesn't get radioactive the same way water
Speaker 2: does because it doesn't react.
Speaker 1: To stuff exactly, it's inert.
Speaker 2: Awesome, Okay, so it makes less bad waste that's also
Speaker 2: easier to clean up while not having this explosion risk.
Speaker 1: Yeah, exactly. And so this is very promising and there's
Speaker 1: a bunch of private industry developing this technology. It's like
Speaker 1: exploding right now. And I talked to a nuclear chemist
Speaker 1: here ECI and asked, like, is this real or is
Speaker 1: just just like private industry hype? And she said, no,
Speaker 1: it's real. The tech has been demonstrated. We know this works.
Speaker 1: It's really just a question of getting it regulated and
Speaker 1: getting the economics to work.
Speaker 2: All right, So it sounds like it's all upsides for
Speaker 2: this particular reactor. Are there any downsides?
Speaker 1: So you know, this is a newish technology. There's still
Speaker 1: developing it. There's only seven that have ever been made.
Speaker 1: Two of them are operating now in China. And in
Speaker 1: some cases there were issues, like there's a reactor in
Speaker 1: Germany where they had exactly the problem that you were
Speaker 1: talking about. The graphite pebbles were rubbing against each other
Speaker 1: and they made dust, and the dust is radioactive. It
Speaker 1: has caesium, has strontium. It's not good, and so there's
Speaker 1: always risks there. But you know, people are working on
Speaker 1: this technology. It's new, it's promising, it's definitely not perfect.
Speaker 2: Okay, awesome, So let's move on to the last kind
Speaker 2: of new reactor that we're going to be talking about today,
Speaker 2: which is liquid metal salt, which is definitely the most
Speaker 2: awesome sounding of the reactors.
Speaker 1: I know, it's super cool and it sound that is
Speaker 1: much more dangerous. And the idea is, let's avoid again
Speaker 1: having very high pressure water. That seems bad, so let's
Speaker 1: replace the water with something else that doesn't need to
Speaker 1: be super high pressure in order to stay liquid. So metal,
Speaker 1: for example, metal is a very high heat capacity. It
Speaker 1: can remove heat very quickly, and it doesn't need to
Speaker 1: be a super high pressure to stay a liquid. Right,
Speaker 1: It's not going to want to turn into gas because
Speaker 1: this boiling point is much much higher, and so you
Speaker 1: can have, for example, liquid metal flowing through your reactor
Speaker 1: at basically one atmosphere. It's still super duper hot, but
Speaker 1: now it's liquid metal instead of liquid water, which you're
Speaker 1: forcing to stay liquid. It's like very happy to stay
Speaker 1: a liquid.
Speaker 2: Wow. So if the reactor cools off, is it hard
Speaker 2: to get that metal to be liquid again or no,
Speaker 2: you just get the reaction going and it melts happily.
Speaker 1: That's actually one of the safety mechanisms, right, is they
Speaker 1: have a plug at the bottom made of metal that
Speaker 1: melts at a slightly higher temperature, and if the core
Speaker 1: or ever overheat past a certain temperature, it melts the
Speaker 1: plug and all the metal just drips out and then
Speaker 1: it cools, and now you have this big solid so
Speaker 1: it's not like exploding everywhere. It can't melt down anymore, right,
Speaker 1: because the fuel also is dissolved into the metal. In
Speaker 1: the case of the water, you have like the water
Speaker 1: flowing around the fuel rods. Here, you take the uranium
Speaker 1: directly into your liquid metal. The reaction is happening within
Speaker 1: the metal, but if it ever overheats, it breaks the
Speaker 1: containment and just drips out and then cools, and so
Speaker 1: it's all good. So it's much safer.
Speaker 2: That's such a cool passive solution. Like if something catastrophic
Speaker 2: happens and all the humans need to leave it sounds
Speaker 2: like it solves the problem on its own with no
Speaker 2: humans there to help. That's fantastic exactly.
Speaker 1: So the pressurized water reactor needs active containment, and this one,
Speaker 1: if it fails, it just basically cools itself down, so
Speaker 1: no risk of overheating or melt down. And it's liquid
Speaker 1: metal or salt, because you can do the same thing
Speaker 1: with what we call salts in the periodic table, you
Speaker 1: know whatever. It's just another l element which, if you
Speaker 1: heat it enough, turns into a liquid and has all
Speaker 1: the right chemical properties you can dissolve uranium into it,
Speaker 1: has the right boiling and melting points, et cetera, et cetera.
Speaker 1: So they have these experimental reactors using liquid metal or salt,
Speaker 1: and this is one of the designs that was explored
Speaker 1: early on in the history of nuclear power and then
Speaker 1: ignored because the military wanted to use pressurized water reactors.
Speaker 2: Oh boo. Okay, so we've talked about the benefits here.
Speaker 2: Does it have downsides?
Speaker 1: I mean, I think it's mostly upsides. The only downside
Speaker 1: here is that we don't have as much experience, so
Speaker 1: it's not as proven like we've been using pressurized water
Speaker 1: reactors for decades we know how they work, we know
Speaker 1: how they fail. Liquid metal and salt reactors are just
Speaker 1: much more experimental, but they have a lot of other
Speaker 1: potential upsides. For example, you can use other fuels than
Speaker 1: just uranium. You can use for example, thorium. Thorium is
Speaker 1: awesome because it's not fissile on its own right. You
Speaker 1: need to start off with some neutrons to hit the thorium,
Speaker 1: and then the thorium will convert into uranium two thirty three.
Speaker 1: Urinium two thirty three is another isotopic uranium. It's much
Speaker 1: better for these reactions, and then you don't produce any
Speaker 1: weapons half life. You can also use thorium reactor to
Speaker 1: burn fuel from other reactors. So you take like the
Speaker 1: byproducts of a light water reactor, you can put it
Speaker 1: into your thorium reactor and it will burn it. It
Speaker 1: will use up some of that fuel. Remember that we
Speaker 1: talked about light water reactors mostly burn the uranium two
Speaker 1: thirty five. The two thirty eight turns into all this
Speaker 1: other stuff. You can take all that stuff and put
Speaker 1: it into a thorium reactor and it will burn it.
Speaker 2: It will burn the nasty stuff and turn it into
Speaker 2: not nasty stuff.
Speaker 1: It turns it into less nasty stuff. Exactly. The waste
Speaker 1: here has much shorter half lives, so you can take
Speaker 1: stuff that starts out with millions or thousands of years
Speaker 1: of half life and turn it into stuff with tens
Speaker 1: or hundreds of years of half life. So that's really good.
Speaker 1: And it can't make plutonium, so there's no weapons byproduct.
Speaker 1: And thorium already is a product of rare earth mining,
Speaker 1: like you're digging for a zinc and cadmium and all
Speaker 1: sorts of other stuff you need for fancy technologies. Thorium
Speaker 1: is a waste product. We're already producing huge amounts of
Speaker 1: thorium in our industry, so thorium is a really an
Speaker 1: excellent direction for nuclear technology.
Speaker 2: You said it's a waste product, so it's stuff we're
Speaker 2: currently just throwing out.
Speaker 1: Yeah, exactly, and with huge deposits of it. India has
Speaker 1: massive access to thorium, for example, and so a lot
Speaker 1: of it. Countries around the world, China, India are developing
Speaker 1: these thorium reactors, again more experimental, so there could be
Speaker 1: things we don't understand about them yet because we just
Speaker 1: haven't spent thirty years watching them fail, but it's definitely
Speaker 1: a good direction.
Speaker 2: Okay, all right, So we've talked about some new designs,
Speaker 2: we've talked about the old designs. Let's back out and
Speaker 2: take a big broader picture. I feel like I'm hearing
Speaker 2: more about nuclear reactors as the impacts of global climate
Speaker 2: change are sort of becoming more day to day and
Speaker 2: bearing down upon us. And so what do you think, Daniel,
Speaker 2: do we need advanced nuclear reactors to deal with global
Speaker 2: climate chain.
Speaker 1: I think it's going to be part of the future.
Speaker 1: I mean, currently nuclear power provides like five to ten
Speaker 1: percent of the worldwide energy use. It's like twenty ish
Speaker 1: percent in the United States. Some countries like France, it's
Speaker 1: a much much higher fraction. A lot of those reactors
Speaker 1: are really decades old, like the United States has really
Speaker 1: old reactors, as our rate of turning on new reactors
Speaker 1: is dropped basically to zero. But nuclear power is also
Speaker 1: very attractive for lots of reasons, like it's very constant.
Speaker 1: You turn on nuclear power plant, it's going to pump
Speaker 1: out energy day and night, rain or shine, wind or
Speaker 1: no wind doesn't really matter. And so on one hand,
Speaker 1: that's great to supplement things like wind and solar, which
Speaker 1: do fluctuate obviously day to night and windy to not windy.
Speaker 1: What you actually want, though, to supplement renewables is not
Speaker 1: something like nuclear that's hard to turn on and off,
Speaker 1: but something you can turn on and off very quickly,
Speaker 1: because you don't want to be running a nuclear power
Speaker 1: plant when you already have too much energy on the
Speaker 1: grid from solar. You want to shut it down then
Speaker 1: and then turn it back on during the night. But
Speaker 1: nuclear power plants are hard just to turn on and
Speaker 1: hard to turn off, so they're very constant.
Speaker 2: One of the things I really loved about atomic Dreams,
Speaker 2: and one of the things that we don't end up
Speaker 2: getting into in our interview with Becca, is that you
Speaker 2: can take those times when you don't necessarily need the
Speaker 2: nuclear power and you can do things like run a
Speaker 2: desalination plant, which would be very helpful in California that's
Speaker 2: having all these issues with fresh water. So there's things
Speaker 2: that you can do to make up for the fact
Speaker 2: that nuclear power is not easy to turn on or
Speaker 2: off to you know, still make it beneficial.
Speaker 1: Yeah, exactly, And it seems like definitely part of our
Speaker 1: portfolio in the future. The UN has all these different
Speaker 1: pathways to limiting the warming of the planet to one
Speaker 1: point five degrees, and every single one of those pathways
Speaker 1: includes nuclear power and expanded nuclear power on top of
Speaker 1: what we already have. So I think it's an important
Speaker 1: quiverent in our arsenal. It's definitely not perfect and the
Speaker 1: definitely issues with it, And boy do I wish we
Speaker 1: just had fusion around the corner.
Speaker 2: That's the man.
Speaker 1: But you know, we're in an imperfect situation. We have
Speaker 1: imperfect options. And next time we'll talk all about the
Speaker 1: pluses and minus and whether nuclear power is good or
Speaker 1: bad for the environment on the whole.
Speaker 2: All Right, So in the next episode we're going to
Speaker 2: be talking to Becca, and in particular, we're going to
Speaker 2: be talking about how public perception is impacting the rollout
Speaker 2: of nuclear power, things like fear from the reactor meltdowns,
Speaker 2: what to do with the waste, problems with licensing, etc.
Speaker 2: So we look forward to seeing you on Thursday for
Speaker 2: that conversation. Daniel and Kelly's Extraordinary Universe is produced by
Speaker 2: iHeart Reading. We would love to hear from you, we
Speaker 2: really would.
Speaker 1: We want to know what questions you have about this
Speaker 1: Extraordinary Universe.
Speaker 2: Want to know your thoughts on recent shows, suggestions for
Speaker 2: future shows. If you contact us, we will get back
Speaker 2: to you.
Speaker 1: We really mean it. We answer every message. Email us
Speaker 1: at Questions at Danielandkelly dot org.
Speaker 2: We can find us on social media. We have accounts
Speaker 2: on x, Instagram, Blue Sky and on all of those platforms.
Speaker 2: You can find us at d and K.
Speaker 1: Universe will be Chye. Write to us